


Warming the Bones

by SoloShikigami



Category: Undertale (Video Game)
Genre: M/M, Multi, Polyamory, Sibling Incest, Threesome - M/M/M
Language: English
Status: Completed
Published: 2020-03-09
Updated: 2020-03-09
Packaged: 2021-02-28 17:20:50
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,316
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23080858
Author URL: https://archiveofourown.org/users/SoloShikigami/pseuds/SoloShikigami
Summary: Sans finds there’s room in his heart for one more, Papyrus wants him to be happy and agrees, and the three monsters find themselves navigating the tricky waters that can be a poly relationship.
Relationships: Grillby/Papyrus/Sans (Undertale)
Kudos: 28





	Warming the Bones

**Author's Note:**

  * For [SesuRescue](https://archiveofourown.org/users/SesuRescue/gifts).



> An expansion of the Drabble "Barred" (Chapter 126) for SesuRescue!

“Hey, uh, Papyrus? Can I talk to you for a sec?”

“Of course, Sans!”

Papyrus went into the living room to find Sans sitting on the couch. The smaller skeleton looked a bit sad and almost worried, his hands in his lap, fidgeting nervously. Papyrus frowned and sat next to him.

“Sans, is something wrong?” Papyrus asked, putting a hand on the other’s knee.

“No, well, maybe, I mean, it’s not serious, but it kind of is,” Sans stammered.

Papyrus smiled at Sans encouragingly. This reminded him of some months ago when they were in a similar position. Sans had sat him down and confessed the feelings that he had for his younger brother through nervous stammers and blushing stutters.

“Breathe,” Papyrus prompted Sans after a moment.

Sans stopped speaking, taking a moment to take a deep breath through his nasal aperture and let it out slowly through his teeth.

“Sorry,” Sans murmured. “Just, I, I’m not sure how to say this.”

“Whatever it is, Sans, you can tell me. I can take it,” Papyrus gently coaxed.

Sans sighed. “I, I’m sure you can, it’s just…”

As Sans trailed off, Papyrus felt his soul sink. What if this was something really bad? What if Sans realized that he didn’t really have romantic feelings for Papyrus? The tall skeleton knew that his mind was starting to run away without him a bit, and he tried to reel it in before Sans finally found the courage to get to the reason for his nervousness.

“Papyrus, do you believe a monster can be in love with two souls?” Sans asked in a bit of a rush. “Or do you think there’s just one soul to another?”

Papyrus took a deep breath himself, though it was quiet and subtle. His worries were mostly eased, however, new ones were taking its place.

“I suppose so?” Papyrus asked. “It’s honestly not something that I have given a lot of thought to. What brings this up all of a sudden?”

He saw Sans’ face light up a little with a blush.

“Uhm, well, okay first I have to make this absolutely clear,” Sans looked up and locked eyes with his brother. “Papyrus, you mean the world to me. I love you very, very much, and I cannot imagine my life without you.”

Papyrus smiled in return, his soul lightening a little. “I know.”

“Sure, but I still wanted to say it so you’re clear with how I feel about you.”

“Thank you, Sans, I love you too.”

Papyrus leaned forward and kissed Sans on the forehead.

“Okay, good. That being said, I’ve been having feelings for Grillby.”

Papyrus blinked. On one hand, he wasn’t particularly surprised; Sans and Grillby had been friends for a very long time and he was probably the only monster in the Underground who knew Sans better than he did. Papyrus knew he told Undyne things that Sans probably didn’t know, it was the way a relationship between best friends worked.

“Would you mind elaborating? How long have you been having feelings like this?” Papyrus asked, his tone even and gentle.

Sans’ body seemed to let go of some of the tension that made him rigid.

Some, not all, though.

“I’m in love with him,” Sans confessed. “It’s a little different, but I’m pretty sure that’s what I’m feeling. Dunno how long exactly, but it’s become more pronounced in the past month or so, now.”

“Oh, Sans,” Papyrus shook his head. “Why didn’t you say something earlier? I hope you haven’t been tormenting yourself over this.”

If Papyrus had learned nothing else about Sans since they started being more romantically intimate with one another, he learned that Sans has a tendency to be very self-destructive in a mental and emotional way.

“No, no, I haven’t been tormenting myself. I seemed to feel it more but I waited to see if it was something for real or if it was one of that friendly kind of crush. You had a crush on Undyne at one point, remember?”

Papyrus snickered a little; it was a few months after Undyne had started switching some of Papyrus’ physical training to his extra special one on one training in the kitchen. The close proximity of the two monsters working in a heated kitchen together seemed to bring out Papyrus’ want to make it more romantic. He spent a couple of weeks pining over Undyne, borrowing poetry books hidden under puzzle books from the Librarby, sighing as he would stare out the window, even his cooking attempts seemed unfocused, and finally Sans got him to talk about it. The older brother’s advice was to confess his feelings to Undyne, but Papyrus felt himself getting rather shy around Undyne. It wasn’t until one day when Undyne had to call Alphys for something and she instead asked Alphys about the weather. Papyrus teased her about the call, but he had put two and two together and realized that Undyne wasn’t into him. The odd thing to Papyrus was that he expected to feel very heartbroken, and while he was definitely disappointed, it wasn’t the soul-crushing experience he was sure would happen. After another conversation with Sans, he concluded that it was no more than a friendly little crush one sometimes got on a friend, and that there were likely no true romantic feelings involved.

“I do understand,” Papyrus said. “Well, I am glad that you haven’t been putting yourself under any unnecessary emotional stress. So, what do we do now?”

“Now I ask you a pretty hefty question; how would you feel about opening our relationship to another partner?”

Papyrus blinked. “What do you mean?”

“How would you feel if Grillby joins us?”

“If you want to date Grillby, I mean, I suppose I don’t see why not.”

“I would want him to date you, too.”

Papyrus felt his face warm. “Erm, well, I, I don’t know about that, Sans.”

Sans tilted his head, looking concerned. “Why do you say that?”

“It’s, well, it’s, it’s nothing.”

“Bullshit. It’s never nothing when it comes to your feelings, Papyrus,” Sans reached over to grip one of Papyrus’ hands, then brought it closer to himself and covered it with his other. “Also, if something like this is going to work, we all need to be open and honest with one another and be on the same page.”

“I see. Well, I guess I just don’t know Grillby very well. He is a very nice-looking monster, he is very kind, and I may not like his restaurant, but he is good to you and that’s really been the majority for my concern.”

“There sounds like there’s a ‘but’ in there, bro.”

Papyrus used his free hand to scratch the back of his head. “Maybe? I don’t know, Sans. Just, I guess…”

“Come on, Papyrus,” Sans said gently, squeezing his hand. “Please tell me.”

“Grillby is your friend, Sans. He and I have barely spoken, and my dislike for his restaurant is almost as well known as your jokes. I just cannot imagine that he could ever develop feelings for me enough to want to date me,” Papyrus smiled at Sans and squeezed his hands in return. “But if you would like to date him, and he reciprocates, I’m perfectly all right with that.”

“Aw, Paps, you may not like Grillby’s food, but that doesn’t mean you don’t like him, right?”

“I do not know him well enough to say one way or the other.”

“If you are against exploring bringing in another partner, we don’t have to. I’m not going to be upset. But, if you’re willing to give it a shot…”

Sans ran his fingers over the top of Papyrus’ hand, falling silent to give him time to think.

“The Great Papyrus cannot back down from a challenge, can I?” Papyrus said after a few moments of silence.

Sans grinned and gave a small huff of laughter. “Well, that’s true, just as we go along in this, I want you to be honest with me,” Sans’ face dropped into a more serious look. “This isn’t going to be worth anything if you’re suffering in silence.”

“As long as you are open and honest in return,” Papyrus said. “And of course, this all goes for Grillby as well.”

“Of course.”

Sans’ grin brightened a little, Papyrus smiled and the two leaned in to kiss each other gently and passionately, reaffirming the love that they had for one another.

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

Sans had been sitting at the bar in Grillby’s for the majority of the evening. While it wasn’t unusual for Sans to be seated at the bar, and it wasn’t unusual for him to stay so late, his silence was.

Grillby was always on the fence about whether or not fate was a thing, but he felt that if there was, it decided to grace his humble restaurant that evening. While it was getting late in general, the place cleared out a little earlier than expected. He had lost count how many bottles of ketchup he had slid over to his favorite (and only) skeleton customer and friend. Sans had been his quiet self this evening, only lifting a hand or his bottle of ketchup in greeting to any of the other monsters that came into the bar, no jokes, no puns; perhaps he was just tired.

“No one else is here, huh?” Sans said after it had been quiet for about twenty minutes.

Grillby nodded, bending down to wet a rag with some cleaning solution, and then he started to clean the bar in slow circles.

“Think it’s okay if I ask you something?” Sans asked, his voice dropping in volume, despite the fact that the two monsters were completely alone.

Grillby nodded, keeping a neutral look on his face though in his mind he was concerned as well as curious. Sans normally didn’t ask him things, unless he was drunk with exhaustion.

“You got your eyes on anyone lately?”

Grillby’s wiping slowed down more.

“I suppose you could say I do,” Grillby said softly.

“Yeah? Tell me about them.”

Grillby made a small smile. “I enjoy his company.”

“Come on, man, that can’t be it,” Sans prompted when he realized that Grillby wasn’t continuing.

“It is not,” Grillby confirmed. “Though I am… _sans_ a good turn of phrase to describe him.”

Sans chuckled. “Good one.”

“Yes, he is.”

Sans was then made very aware of how close Grillby was to him; the fire elemental had sidled closer and closer to the skeleton until they were inches apart, the bartender leaning against the bar a little to one side but turned to face him.

Sans met his gaze with the ketchup bottle halfway to his mouth. “W-wait, are you serious?”

“Joking is your job, Comic.”

“Why haven’t you said anything before?”

“You never asked.”

“Oh.”

“Also, aren’t you with Papyrus?”

“Yes.”

“There is your answer. I don’t make it a practice to be a homewrecker, Sans.”

Grillby stood back up and went back to cleaning.

“Well, you don’t have to be,” Sans murmured, shaking the bottle in his hand slightly to see how much was left.

“What are you talking about?”

Sans looked up and grinned wider at him. “Papyrus and I have been talking. See, you’re not the only one harboring a secret crush on their closest pal.”

Grillby stopped cleaning and turned his full attention to Sans.

Sans chuckled and set the bottle of ketchup aside, his hands meeting, his fingers tangling themselves together. He took a deep breath to try to calm himself before he continued to speak.

“I’ve like you a bit more than just a friend for a while, Grillby,” Sans explained. “I think it even developed before Papyrus and I began our romantic relationship. I’ve always known I had room in my soul for more than one monster. Papyrus is completely aware why I am here tonight. So, I guess the question is, would you be open to dating the both of us?"

Grillby took a moment to consider the skeleton in front of him, then another to consider the one who was currently absent.

"And Papyrus consented to this?" he asked.

"He did."

"I was under the impression that he despised me; if it wasn't the disapproval of my menu, it was that he likely blamed me for how much time you spent here."

Sans chuckled. "I was a little worried about that, too. He’s worried that you might not like him because he's very loud with his opinions."

"I have never held that against him. He has every right to express his feelings."

"I figured you would say something like that, you're not the kind of monster to hold a grudge."

Grillby nodded. "So, what do we do now?"

"Are you free tomorrow night?"

\-----

"I'm still a little unsure about this, Sans," Papyrus said, shuffling his feet as the two waited outside the MTT Resort Restaurant.

"It's just a date, Pap; we're going to take all of this nice and slow," Sans assured him.

"I just hope that I am dressed appropriately,” Papyrus gave Sans a once-over. “You should have put at least a little more effort in your clothing choice, Sans. The dating manual says you should dress nice to show your date that you care!"

"Nah, Grillby knows I care."

"How?"

"He told me."

The two skeletons nearly jumped when the new voice joined them.

“Sheesh, you sure know how to make a guy jump out of his skin,” Sans quipped, grinning up at the tall fire elemental.

Papyrus rolled his eyes and groaned.

“You do not have skin, Sans,” Grillby said with an affectionate tone.

Sans shrugged. “Hey, you already got me rattled.”

“SANS, NO!”

“Sans, yes.”

“Is this what it’ll be like all though dinner?” Grillby said with a small laugh.

“No, my brother has long since promised that he will not pun during meals,” Papyrus said.

“I see. You have chosen a very interesting outfit this evening, Papyrus.”

A small blush bloomed on Papyrus’ face and he looked away. “Thank you, Grillby.”

It was his usual dating outfit; his “Cool Dude” shirt with the basketball shoulders, a pair of denim shorts, and sneakers along with his backwards baseball cap. Papyrus was feeling a little self-conscious next to Grillby, while he didn’t look too much different than when he was working, the black slacks and white button-down shirt was much more formal. But he had left his black bowtie behind and a wild-looking jacket with multiple bright colors was slung over his shoulder.

“Well, let’s get going,” Sans said. “I’d hate to waste all the reservations that I made for us.”

They were seated at Sans’ favorite table, their orders taken, and Sans secretly held his breath in anticipation for how the evening was going to go.

The dinner went fairly well. The three had held up very pleasant conversation; Grillby asked Papyrus about his puzzles, Sans interjected with puns now and then, and Grillby shared some stories about Snowdin before the skeleton brothers had moved there.

"Wowie, that was a spectacular dinner," Papyrus said as they walked out.

"Eh, I know someone who can do a bit better," Sans said, nudging Grillby with his elbow.

Grillby rubbed the back of his head, looking a little embarrassed, it seemed.

"I think they have an admirable chef on staff," Grillby said, but then he straightened and gave Sans a wink. "However, yes, I could."

Sans grinned up at him and then looked past him at Papyrus. “And of course, my bro is the Master of Spaghetti-making.”

“Nyeh, heh, heh, almost!” Papyrus said, looking pleased with the compliment for a moment before dropping into a more uncertain expression. "What are we going to do now?" he asked.

"A stroll through Waterfall might be nice," Grillby suggested.

"Sounds good," Sans said, reaching over to take Grillby's hand, the fiery fingers slipping between his phalanges like they belonged there.

Papyrus saw the gesture and he saw the small look the two shared. He felt shy all of a sudden, wondering if he should be there, wondering if this all was really a good idea…

Suddenly, a gentle warmth wrapped around his own hand, and Papyrus looked up to see Grillby smiling at him.

"What do you think, Papyrus?" he asked, squeezing his hand slightly.

"I, I think that's a wonderful idea," Papyrus murmured, giving Grillby a small smile in return.

Sans knew that tone and he knew that blush, and he could not have been more pleased as the three of them walked hand in hand in hand towards Waterfall.

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

The rest of their date went well enough; they strolled through the room full of echo flowers, stopped to gaze at the crystals that made their stars, and nearly lost Papyrus to one of the small ponds when he became a little too animated when talking about one of his training sessions with Undyne.

"Heh, I thought you were supposed to be falling for me," Grillby said with a small smirk when he pulled Papyrus back from the edge of the water.

Papyrus groaned. "Oh, no, my brother's horrible puns have infected you too!"

Both Sans and Grillby laughed. They had decided at that point that it was getting late and they headed back to their home in Snowdin.

"Thank you, Sans and Papyrus, I had an enjoyable evening," Grillby said when they approached the home of the two skeletons.

“Yeah, this was fun,” Sans said.

“I agree! This was quite pleasant!” Papyrus said brightly. “I would very much like to do it again, that is, if you both would like to.”

“I’d like to,” Sans said.

Grillby nodded. “I would as well. Are you two free the night after next?”

“I believe so,” Papyrus said.

“I’m game, what did you have in mind?” Sans asked.

“I’ll think of something,” Grillby said. “Well, I guess this is goodnight.”

“I guess it is,” Sans said.

Papyrus realized with a small bit of a start that Grillby was standing closest to him. The dating manual flashed in his head for a moment, the chapter titled “Seal the Deal!” mentioned a good night kiss at the end of a successful date. While Papyrus would be the first to admit that the date was quite successful, this wasn’t a one on one date. The dating manual covered double dating, but that wasn’t what this was either – double dating required two couples – and Papyrus panicked as Grillby leaned closer.

“WHOOPSY DOOPSY, I JUST REMEMBERED, I NEED TO FEED THE PET ROCK!” Papyrus suddenly exclaimed. “YOU TWO HAVE FUN!”

With that, Papyrus turned and jumped through the living room window.

“Heh, isn’t my bro the coolest?” Sans said, grinning proudly.

Grillby blinked. “Is he all right?”

“Oh, sure, that’s what he does when he needs to leave quickly, something he picked up during training,” Sans explained, though the bigger implications made him wince slightly. “I, uhm, I hope you don’t take his reaction the wrong way. Papyrus likes you a lot, I can tell.”

“Is that so?”

“Oh, sure, he’s not the type to mince words. If he didn’t, he would have been honest and upfront. It’s when he likes you that he starts getting nervous and feels the need to make excuses.”

“Sounds like he’s been hanging around one of those Tsunderplanes.”

Sans chuckled. “Nah, he’ll be honest if you ask him, trust me. He’s adorable when he gets all flustered though.”

Grillby chuckled. “I see. Well, I wouldn’t feel right being uneven with you two,” Grillby reached down and took Sans’ hands in his and brought them close to his mouth, his hot breath a wave across Sans’ bones. “I will see you both later?”

Sans nodded. “You will see us both later.”

Grillby smiled, letting go of Sans’ hands somewhat reluctantly before turning to head home. Sans watched him for a little bit, and then went inside to talk to Papyrus.

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

Two weeks later, the three of them had gone on several dates and their relationship was evolving, though it was evolving very slowly. That worked out well enough for Papyrus, but Sans was not quite as patient.

“Did you know that Grillby won’t kiss me until he kisses you?” Sans brought up one day while Papyrus was warming up some spaghetti for their lunch.

“I did not. Why?”

“Because he’s classy like that. It’s his way of making sure one of us doesn’t get more attention than the other.”

“It is very nice of him to be so considerate. I’m sorry if it’s stagnating the relationship, I know how much you enjoy intimate, physical contact.”

“Heh, well, I do, but of course I want a bit more than just kisses from both of you.”

Papyrus felt his face heating up, and it wasn’t because of the steam from the pot of spaghetti and sauce that he was stirring. After a moment, he sighed and turned off the burner on the stove and he sat at the table.

“I do need to speak with you about all of this,” Papyrus said softly, staring at the table’s surface.

“Please do,” Sans said, reaching across to put his hand over his brother’s. “If you aren’t comfortable with it, we can end it. Grillby will understand, it will be okay.”

“What about you?”

“I do have to admit that I’d be disappointed, but you mean a lot to me, Papyrus. If you need a monogamous relationship between just you and me, I can give you that.”

Papyrus nodded slightly, but he didn’t look up. “One of the things that concerns me most about this is what if one of us loves one more than the other?”

“Would you say you love me more than you love Grillby?”

“A little? I, I hate to say such a thing, it sounds horrible as it doesn’t really explain how I feel.”

“Try your best, Paps.”

“I am developing feelings for Grillby. He is a wonderful monster and he is treating us very well. I am glad that you told me his reason for not kissing you, as I was wondering why he seemed reluctant to be intimate with either of us. Granted, we have been out in public, and maybe he is only affectionate in private.”

“We can test that theory,” Sans said with a wide grin, but then it settled back into a more neutral look. “But seriously, Papyrus, is this working for you so far?”

Papyrus finally looked up and nodded. “So far.”

“Good. I’m not sure if this will make you feel any better, and while I can’t say I love one of you more than the other, there is just a different kind of love I have for Grillby compared to the love I have for you. I can’t really describe it, either, but I do know that I care about you both very much and would do anything to make you both happy.”

Papyrus smiled and turned his hand so he could squeeze Sans’ in return. “While the notion is noted and appreciated, if you’re happy then we will be happy. You mentioned testing the theory that perhaps Grillby does not give too many public displays of affection?”

“Yeah, but first, why haven’t you let him kiss you?”

Papyrus looked away again, his blush becoming more apparent. “I… Well… oh, come on, Sans, you know how long it took me to gather the courage to kiss you!”

Sans laughed. “I thought you were going to pass out on me, you were so nervous, then embarrassed, and damn it, Papyrus, if it wasn’t the cutest and hottest thing I have ever seen. Now I’m a little curious what it will be like to watch you kiss Grillby for the first time.”

Papyrus pulled his hand away and crossed his arms. “If you keep teasing me like that, it will not happen.”

“Aw, come on, Papyrus,” Sans’ grin sobered into a sincere smile. “But, seriously, go at your pace, we love and respect you.”

Papyrus nodded. “I love you, too. Now what was this idea of yours? I’m rather curious.”

“Well, there was an announcement the other day that Mettaton is releasing a new movie this weekend, so…”

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

The three sat on the floor in the living room, the two skeletons on either side of Grillby, full of dinner, empty of worries, and Mettaton reclining on the television screen as flower petals showered over him.

“This has been going on for more than half an hour,” Grillby whispered to Sans.

“I know,” Sans chuckled. “Can you believe this guy?”

“Shhh!” Papyrus hushed them. “Do neither of you know how to conduct yourselves while watching a movie? I expected this sort of behavior from Sans, but I must admit, Grillby, that I am quite surprised by you.”

Grillby glanced at Sans, who looked at him back and the two shared a small twinkle in their eyes.

“I do apologize, Papyrus,” Grillby said gently. “However, I can think of a few other things that might a little more intriguing.”

“Oh? What is it?” Papyrus asked.

The smile on Grillby’s face grew ever so slightly. He turned to Sans and brought a hand up to caress the short skeleton’s cheek.

“If I may?” the fire monster asked, his thumb running just under Sans’ teeth.

“Thought you’d never ask,” Sans murmured.

The kiss was gentle, just a bare pressing of their mouths for a moment until Grillby leaned in even more, deepening the kiss slowly. Sans hummed in appreciation, pressing back eagerly, opening his mouth slightly to allow his magic reach for Grillby’s.

Papyrus blushed at the display, turning away for a second, but then looking back to watch when he heard the small noises coming from his brother. Mettaton’s movie was completely forgotten by one of his most loyal fans as he was instead drawn into the sight of intimacy before him.

Sans opened one eye slightly and saw Papyrus watching. He took note of the blush across his baby brother’s face and the slight lean forward that signaled his interest was caught. It was a small challenge to take the moment to observe Papyrus, as Grillby was an excellent kisser and Sans quickly allowed himself to be lost in his attention for another few moments before pulling away. He brought his hands up, cradling the warm face as he nuzzled it gently.

“That was amazing,” he breathed, his gratitude shining in his eyes before he glanced past Grillby at Papyrus and gave the other skeleton an encouraging look.

“That was very nice,” Grillby agreed, parting from Sans and turning to Papyrus, reaching for his hand. “I’d like to kiss you, Papyrus, if you’re ready for it.”

“Oh, uhm, yes, I am ready,” Papyrus said quickly, but he was unable to meet the eyes of either his brother or Grillby.

Papyrus' soul began pounding in his rib cage as Grillby turned to him. He finally looked up and he could see Sans just past Grillby’s shoulder giving him a loving smile and a slight nod. Papyrus fought down the urge to start breathing heavily, and jumped a little when a warm hand pressed against his cheekbone.

"Are you sure that you’re all right?" Grillby asked gently.

"Oh, sure, sure, of course, why wouldn't The Great Papyrus be all right? Nyeh, heh, heh..."

Grillby smiled, his eyes lidded slightly, a soft but passionate look flickering in his eyes.

"Relax," he murmured, leaning in closer.

Papyrus flinched unconsciously.

"If you don't want to," Grillby murmured, giving him room to back out if this wasn’t something that he wanted.

"I, I do, it's just..." Papyrus' voice trailed off as he felt a small shiver steal through him. "I d-don't want t-to disappoint you."

Grillby chuckled. "I don't believe The Great Papyrus ever could."

Papyrus' soul warmed, and then he leaned forward to meet Grillby's mouth with his own.

Papyrus was a little surprised; he expected a lot more heat, what with Grillby being a fire elemental, but it was a simple warmth and a bit of spark as their magic slowly met. Papyrus was a little timid, but Grillby didn't mind and he kept the kiss slow, gentle, and didn't press to go quite as far as his kiss with Sans. After a moment, though, Grillby was surprised when Papyrus was the one who pressed forward and he felt the skeleton's tongue gently probing at his mouth, asking for entrance. Grillby granted the wordless request, and he moaned as Papyrus explored his mouth; it was still a touch timid and slow, but he was thorough.

Again, Grillby wouldn’t have expected anything less from Papyrus.

Sans watched intently. His soul had also been pounding with nervousness; he wanted so, so much for this relationship to work out, he never remembered wanting anything so badly in all his life, but he also didn't want the two most important monsters to him to be hurt in the process. He knew Papyrus was nervous and Grillby was apprehensive - both wanted Sans to be happy and of course neither wanted to disappoint him or the other.

But there seemed to be no cause for concern; Papyrus and Grillby were enjoying themselves and each other, and Sans' soul soared with happiness when Papyrus gained more confidence. It was also then that Sans wondered if he had a voyeur kink, because he was really enjoying watching his lover kissing their potential partner.

"Whoa," Grillby breathed when the two parted.

"Wowie," Papyrus whispered in agreement.

"Honestly you guys, that was kind of hot," Sans said with a grin.

“Really, Sans?” Grillby said with a touch of lament in his voice.

Papyrus blushed even more and looked away with a touch of embarrassment, but he was also pleased - so much that Sans' pun didn't even bother him this time.

The slight tension that had been present for a good portion of the evening had disappeared and the three went back to watching the movie, though now Sans leaned his head against Grillby's arm and Grillby's hand stroked Papyrus'. Their date ended with gentle, chaste kisses between the three of them, and plans were made for another movie night.

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

The three of them had been dating for about a month, and almost every date included the three of them building more and more intimacy between them. Sans was a flirt, Papyrus was a little shy about it all, and Grillby was a merciless teaser.

“He is driving me crazy,” Sans groaned one night after a date as the two got ready for bed.

“I could tell,” Papyrus said as he pulled on his pajamas.

“How do you stay so calm? I’m ready to jump the both of you,” Sans said.

Papyrus hummed a little in thought. “It doesn’t take much to get you excited.”

“What can I say? I have amazingly sexy partners,” Sans said.

Papyrus looked over to see Sans lying on his side, grinning suggestively at him. He knew that look.

“Flattery only gets you so far, you know,” Papyrus said. “It was your suggestion that we waited until Grillby was ready to be, erm, intimate again.”

Sans sighed, rolling onto his back and folding his hands behind his head. “Yeah, I know. I don’t want to seem to forward or make it seem like this is all about the wild, kinky sex the three of us can have together.”

“SANS!”

“What?”

“Just…” Papyrus sputtered, blushing furiously.

“Ahh, come on, Paps, you’re thinking about it.”

“I am… and… well, I don’t hate it, but… STOP GRINNING AT ME LIKE THAT!”

Papyrus jumped onto the bed to grab a pillow and shove it over Sans’ face. The two had a small pillow and tickle fight before they collapsed into each other, giggling and sighing happily.

“But you are thinking about it, aren’t you?” Sans asked once the two had calmed from their sudden burst of activity.

“Yes,” Papyrus admitted. “Just… nyeh, you know how my confidence wavers. The Dating Manual doesn’t really cover past kissing, and even then, you’ve proven to me that it’s not exactly the most exhaustive volume on such things.”

Sans chuckled; of course, the Dating Manual was written by a human, so kissing seemed to only involve lips, and since as skeletons they had none, Papyrus never knew that there were other ways for skeletons to kiss. He didn’t know about the pleasant spark and tingle they could get when their mouths met, and knew little about using magic to form a tongue, and Sans had the pleasure of teaching him all he didn’t know. As they continued, while Sans was also mostly new to sex and how it would work for them, playfulness, curiosity, and exploration made most of their lovemaking and they enjoyed every bit of it. Sans took the lead most of the time, but as Papyrus’ confidence grew, their roles would switch.

“You are an amazing lover, bro,” Sans said, pulling Papyrus in for a snuggle. “You are attentive, sweet, gentle, and caring. You are a pleasure to please and be pleased by. I’m sure Grillby will enjoy whatever you’re willing to give, and he would love to give you whatever you’re willing to have.”

Papyrus nodded, the two of them kissed, then cuddled under the covers and turned out the light. While Papyrus drifted off to sleep in his brother’s arms, Sans was wide awake and thinking.

~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~

Over the next couple of weeks, the skeletons didn’t see much of Grillby. He had said that he was busy, and the texts between them slowed quite a bit as well. There had even been a few days where they hadn’t heard anything from the fire elemental at all.

“He’s just busy, bro, it happens,” Sans assured Papyrus, who was beginning to worry more and more as the days went on.

Then one night, Sans went out to Grillby’s in the same manner as he did before the three of them started dating. His visits to the restaurant hadn’t completely stopped, but it usually ended with his bringing Grillby back to the house or asking Papyrus if he wanted to meet them in Waterfall.

But this evening, Sans did not come home at his usual time.

Papyrus soon found himself pacing in front of Grillby’s. He hadn’t heard from his brother or Grillby and he was beginning to worry, but he really didn’t want to go inside.

Or did he? Why else would he have come all the way out here; he could have just as easily called either of the two…

Steeling himself for the smell of grease, Papyrus took a deep breath and went inside.

Papyrus immediately noticed the absence of the hated smell. He also noticed that the entire restaurant was empty, save for a short skeleton sitting at the bar, sipping at a bottle of ketchup, and the familiar fire elemental behind it.

“Heh, about time you quit pacing in front of the place like a worried mother hen,” Sans quipped.

Papyrus looked over to Grillby, who was wiping a glass, but he stared at Papyrus intently and had a different smile on his face that Papyrus hadn’t seen on him before.

“I, it, well,” Papyrus stammered, suddenly feeling too hot and shy under the gaze of the other two. “Why didn’t you two come out?”

Sans smirked and waved a hand. Papyrus heard something behind him, he turned to the sound and saw blue magic fading from the door handle - Sans had locked them inside the building.

“What-?” Papyrus started but then was startled when Sans suddenly teleported in front of him.

“Shhh, relax,” Sans murmured, reaching up to press a finger to Papyrus’ mouth. “Come on, bro,” Sans slipped a hand into Papyrus’ gloved one and lead him over to the bar. “Did you notice how nice the place smells?”

“I do not smell anything,” Papyrus said, confusion still evident in his voice.

“Grillby installed a new fan and did some other stuff to get rid of the smell,” Sans explained. “He also has been cleaning the place a little differently.”

“I repainted just about everything,” Grillby explained, setting the glass he was wiping under the bar in its proper place and tossing the rag into a bucket before leaning against the bar towards Papyrus. “I changed a few things on the menu, and researched the best cleaners that would not only cut through grease but leave cleaner, more pleasant smells behind. That is why I have been so busy lately.”

Papyrus felt his soul swell and he looked over at the bartender with a smile. “You did not have to go through such lengths for me, Grillby.”

Grillby chuckled and crooked a finger at Papyrus. The tall skeleton leaned closer to him, and then let out a small shriek of surprise when the collar of his battle body was grabbed and he was pulled partially over the bar and Grillby kissed him gently.

“Of course I did, Papyrus,” Grillby murmured, the words barely heard between the crackling of his flames. “I love you.”

Papyrus blushed. “Thank you. I, I love you, too.”

“And I love you three,” Sans quipped. “Though I’d rather show rather than tell,” he said as he trailed his fingers along Papyrus’ spine.

Papyrus gasped, partly due to the contact, and partly due to what he guessed Sans was suggesting.

“NOT HERE!” Papyrus cried out. “IT IS NOT SANITARY!”

Grillby smirked. “I’ll put a few towels down.”

Papyrus’ protest was silenced by another kiss, Sans continued touching lightly along his spine and then leaned over to lick a long line up the back of his neck. After a moment, Grillby finally released Papyrus, who gasped and fought to get his body and mind back under his control.

“I MUST INSIST!” Papyrus cried out.

Grillby and Sans paused.

“What?” Grillby asked.

“Do you two really want this to be the place where we are intimate for the first time together?” Papyrus asked.

“Hmm, maybe,” Sans said. “I mean, the bar looks amazing, Grillby, and I would love to see either one of you bent over it as I have my way with you.”

Grillby snorted. “Who say we’re going to be the ones bent over it?”

Sans shot him a small smirk. “Uh huh. Anyway, I know the restaurant isn’t the only place you’ve cleaned up.”

Wrapping an arm around Papyrus’ waist and reaching over to grab Grillby’s hand, Sans teleported them upstairs to Grillby’s apartment.

More specifically, the bedroom of the fire elemental.

Papyrus looked around in some slight awe. The room was decorated to be dark, but between Grillby’s natural light and a few candles, there was plenty of light to see yet not enough to be glaring or distracting. The few small windows were covered with a dark, see-through fabric, there was a nightstand with glasses of cool water, a teapot, and three mugs. The room

Papyrus was so busy admiring the room that was so obviously carefully put together, that he was a little startled at the small, familiar arms wrapping around him from behind, one hand sliding along the bottom of the chest piece of his battle body.

"Grillby is very smart. He had a backup plan in case you were not into having sex on the bar," Sans murmured in his ear.

"Oh? That was very thoughtful of you, Grillby," Papyrus said, his body stiffening under his brother’s light touches, nervousness settling in as the reality of the situation began to sink in.

Grillby sensed Papyrus’ nervousness and stood in front of him, taking his hands. “I really want this to be a good night for us. You are, of course, are welcome to postpone this.”

Papyrus could feel Sans flinch slightly at the suggestion. He looked into Grillby’s eyes and saw the love and devotion he had for the brothers not only there, but in his preparations for that evening. Everything that they had went through in the past several weeks ran through his mind, and then it all felt like everything clicked. Everything was going to be all right, he had no more reason to fear, no more reason to worry. They were going to enjoy themselves and each other.

It was Grillby’s turn to be startled as Papyrus leaned forward to catch his mouth in a searing kiss, his flames building slightly between being surprised and turned on by the gesture. He returned Papyrus’ affections and reached around him to find Sans, caressing the short skeleton’s face.

“So, erm, how do we, ah, work this out?” Papyrus asked, moving in to nuzzle Grillby’s neck and starting to unbutton his white shirt.

“Just go with the flow, bro,” Sans murmured, pressing his hands under his armor to caress his ribs.

“That sounds good to me,” Grillby agreed, moving to help lift the chest piece off of Papyrus and setting it aside as carefully as he could while trying to not move away from Papyrus’ attentions.

Papyrus nodded his own agreement as he finished unbuttoning to shirt and pulling it free from the waistband of Grillby’s pants.

“I believe someone is wearing too many clothes,” Papyrus said after a moment, reaching behind to touch his brother.

“I agree,” Grillby said with a smirk, reaching past Papyrus to pull the other skeleton forward so not he was sandwiched between them.

Sans whimpered as Grillby kissed him deeply, helping Papyrus push the blue jacket off before lowering his hands to push down the soft black and white shorts. The kiss had to be broken in order for Papyrus to lift his tank top off, but as Sans’ head was still leaning back, he bent to kiss him, tasting a bit of Grillby’s fire magic left behind.

“I always wondered how sensitive a skeleton’s ribcage was,” Grillby murmured, tracing his finger across the smooth bone and enjoying the kissing intake of breath and the following moan from Sans.

“Quite, especially his,” Papyrus supplied. He reached down to take Grillby’s hand and guided it just inside Sans’ ribcage, pressing his fingers along the insides of the lower ribs. “Especially here.”

Sans cried out as the fire elemental’s warm digits caressed one of his most sensitive areas. Papyrus moved to swallow his cries with another kiss, his fingers wandering across Sans’ clavicles and the outside of his ribcage, which made Sans squirm.

“Enough, please,” Sans pleaded after a little while, feeling his magic beginning to flow and knowing it was a little too soon. He lifted a foot to rub along the side of Grillby’s leg. “Besides, some people here still have their pants on.”

He reached forward to unbutton and unzip Grillby’s slacks, and Grillby bent forward a little to push down the lower portion of Papyrus’ battle body. It was a little tight, but Papyrus helped with a small chuckle and soon the bright blue piece of armor joined the black slacks and track shorts in the growing pile of clothing.

Sans looked between Grillby and Papyrus, admiring the body he knew very well and looking hungrily at the one he was excited to explore. Papyrus smirked and put his hands on Sans’ shoulders as his own eyes roved over Grillby and he bent to murmur against Sans’ skull.

“You do know how to pick them, brother,” Papyrus nearly purred. “What do you think we should do with him?”

Sans hummed in consideration, one hand covering one of Papyrus’. “I think we should find some of his sensitive spots, since you were so kind to tell him one of mine.”

Grillby’s cheeks turned a darker orange, showing his shy side for the first time. Sans could feel Papyrus’ magic hum as Grillby glanced away from them for a moment, and Papyrus took it to move into Grillby’s space, taking his face gently and kissing him. Papyrus then trailed his hands down Grillby’s chest, enjoying the warmth of his flames as they licked between the bones of his hands in an almost playful manner, settling at his hips and pushing the other monster back towards the bed until they both toppled onto it.

Sans watched intently, taking notes of where Grillby’s body turned a darker orange, comparing it to the look on his face, trying to piece together the little things that would speak to him when Grillby might not be able to. He moved towards the bed as well, trailing his hands along Grillby’s legs, brushing briefly between them, drawing a small gasp for the monster.

Papyrus broke their kiss and glanced over to what Sans was doing. He pressed in to kiss down Grillby’s neck and then down his torso. San busied himself by touching delicate spots, discovering new ones on their new partner, lightly encouraging and leading the fire elemental to rest against the pillows proper against the headboard, knowing the path that Papyrus would take.

“I’d like to please you orally,” Papyrus murmured against Grillby’s belly, apprehensive to go lower without permission.

“P-please,” Grillby groaned, his hips hitching up to rub against Papyrus’ body.

Papyrus grinned and continued to move downwards as Sans moved up.

“Hope you can handle him,” Sans murmured as he nuzzled the side of Grillby’s face. “You know how focused Papyrus can get, and he can be a little… intense.”

Grillby was about to respond, but only a groan escaped as Papyrus licked up the underside of his cock. His breath quickened as the skeleton monster went to work, licking along the shaft, circling around the head, and carefully, but firmly, sucking the well-endowed monster down.

Sans continued to kiss Grillby gently, touching him lightly, again taking notes of his reactions to store in his mind for another day. After a little while, Grillby seemed very pleased with Papyrus’ skills, and Papyrus was enjoying himself, and Sans was having a wonderful time watching, but now he wanted to do something. He moved to grab Papyrus away from his task for a moment to kiss him deeply, tasting fire on his tongue.

“I want to fuck you while you suck him off,” Sans growled.

“Mmm, I’d like that,” Papyrus hummed, licking his teeth.

Sans smiled, kissed him again, and let him return to the thick, fiery rod. He moved behind Papyrus and bent to lick along his tailbone and touch along his pelvis, helping his magic to form what he wanted. Papyrus was quite turned on himself, so it didn’t take long for Sans to coax soft folds and a wet hole to form. Sans bent a little lower to drag his tongue through the folds and across the hole which clenched in response as a muffled moan sounded around Grillby’s cock.

“Mmm, please, Sans,” Papyrus groaned.

Grillby also moaned at the view in front of him; Papyrus with his cock in his mouth, and Sans behind him, palming his own forming dick. Papyrus’ tongue was very talented, and the advantage of it being made of magic meant that he would wind it along his shaft, giving Grillby a sensation he hadn’t felt before.

It was incredibly hot to see Sans so sure, so confident, as he lined himself up and pressed steadily into Papyrus. Grillby could feel everything as Papyrus whimpered and moaned around him, before suckling at him harder, conveying the pleasure he was feeling into his task. Papyrus matched his pace to the one Sans set, which slowly built to a fast and hard thrusting, filling the room with the lewd smacks of bone against bone, the squelching of magic, muffled moans, and loud groans from the three monsters as well as the creaking of the bed.

“Fuck, I’m getting close,” Grillby grunted, his hands scratching lightly at Papyrus’ skull.

Papyrus hummed and pulled off. “Sans, I want to move forward.”

Sans nodded, stilling inside of his brother and moving forward with him until Papyrus’ pussy was lined with Grillby’s cock. Seeing what he wanted, Sans helped position Papyrus so his folds would slide along the fiery shaft as Sans began to fuck him again.

Grillby moaned, the warmth and wetness from Papyrus was dripping along his cock and he could feel Sans as he thrust into Papyrus.

Feeling the heat rubbing his clit combined with Sans moving inside of him had Papyrus reaching his climax quickly.

“S-Sans, Grillby,” Papyrus moaned.

“Do it,” Sans groaned.

“Please, Papyrus,” Grillby encouraged.

Papyrus’ body shuddered and he cried out, gripping the bedsheets as he climaxed, coating both cocks in his juices.

“Fuuuuck,” Grillby groaned as the sight and warmth from Papyrus was enough to set him off.

Sans thrust a few more times until he also came, grunting as he filled his brother, then sighing.

Papyrus’ arms were shaking; Grillby noticed and pulled the slender skeleton down into a warm embrace, kissing the top of his skull. He leaned up to grab Sans’ wrist and pulled him down to join them, which he did with a pleased sigh.

“That was wonderful,” Grillby said, leaning over to also drop a kiss on Sans’ skull.

“It was awesome,” Sans said, trailed his hand along Papyrus’ spine.

“Mmmm,” Papyrus hummed, snuggling between the two. “Perfect.”

Grillby smiled at them. “Maybe after a short rest, round two?”

“Heh, you’re as bad as Papyrus,” Sans said.

“And you’re just lazy,” Papyrus muttered.

“Don’t worry, Papyrus, I’m sure between the two of us we can work on his stamina,” Grillby said with a grin. “And if it doesn’t improve, well, we can just tie him up and have our way with him.”

“Oh, no,” Sans said in mock horror. “Whatever have I gotten myself into?”

Papyrus chuckled, glancing up at Grillby, who gave him a wink, and then at Sans, who looked back with a loving grin.

_This will work,_ Papyrus thought to himself, throwing an arm over Sans’ hips as he drifted off to sleep.

**Author's Note:**

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